NF-κB transcriptional activation by TNFα requires phospholipase C, extracellular signal-regulated kinase 2 and poly(ADP-ribose) polymerase-1.
J Neuroinflammation
; 12: 229, 2015 Dec 04.
Article
em En
| MEDLINE
| ID: mdl-26637332
ABSTRACT
BACKGROUND:
The nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) is required for pro-inflammatory effects of TNFα. Our previous studies demonstrated that PARP-1 mediates TNFα-induced NF-κB activation in glia. Here, we evaluated the mechanisms by which TNFα activates PARP-1 and PARP-1 mediates NF-κB activation.METHODS:
Primary cultures of mouse cortical astrocytes and microglia were treated with TNFα and suitable signaling pathway modulators (pharmacological and molecular). Outcome measures included calcium imaging, PARP-1 activation status, NF-κB transcriptional activity, DNA damage assesment and cytokine relesease profiling.RESULTS:
TNFα induces PARP-1 activation in the absence of detectable DNA strand breaks, as measured by the PANT assay. TNFα-induced transcriptional activation of NF-κB requires PARP-1 enzymatic activity. Enzymatic activation of PARP-1 by TNFα was blocked in Ca(2+)-free medium, by Ca(2+) chelation with BAPTA-AM, and by D609, an inhibitor of phoshatidyl choline-specific phospholipase C (PC-PLC), but not by thapsigargin or by U73112, an inhibitor of phosphatidyl inisitol-specific PLC (PI -PLC). A TNFR1 blocking antibody reduced Ca(2+) influx and PARP-1 activation. TNFα-induced PARP-1 activation was also blocked by siRNA downregulation of ERK2 and by PD98059, an inhibitor of the MEK / ERK protein kinase cascade. Moreover, TNFα-induced NF-κB (p65) transcriptional activation was absent in cells expressing PARP-1 that lacked ERK2 phosphorylation sites, while basal NF-κB transcriptional activation increased in cells expressing PARP-1 with a phosphomimetic substitution at an ERK2 phophorylation site.CONCLUSIONS:
These results suggest that TNFα induces PARP-1 activation through a signaling pathway involving TNFR1, Ca(2+) influx, activation of PC-PLC, and activation of the MEK1 / ERK2 protein kinase cascade. TNFα-induced PARP-1 activation is not associated with DNA damage, but ERK2 mediated phosphorylation of PARP-1.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Fosfolipases Tipo C
/
Ativação Transcricional
/
NF-kappa B
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Fator de Necrose Tumoral alfa
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Poli(ADP-Ribose) Polimerases
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Proteína Quinase 1 Ativada por Mitógeno
Limite:
Animals
Idioma:
En
Revista:
J Neuroinflammation
Assunto da revista:
NEUROLOGIA
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Canadá